One of three Syracuse residents indicted last month on gun-trafficking conspiracy charges can avoid jail time if she testifies against her co-defendants, a county court judge agreed Tuesday.

Courtney Everson, 20, of 325 Park St., Apt. 2, pleaded guilty before Judge William D. Walsh to a single count of second-degree criminal possession of a weapon. She had faced three weapons counts, plus counts of fourth-degree conspiracy, fifth-degree criminal sale and fifth-degree criminal possession of a controlled substance.

As part of the plea agreement, Everson is to give statements to the district attorney’s office against her co-defendants, testify at trials, hearings and before the grand jury and keep out of trouble, among other conditions, Walsh said.

If she obeys the conditions, she will be allowed to withdraw the weapons plea and plead guilty to conspiracy, drawing five years probation as a sentence, Walsh said. If she fails to live up to the bargain, she could get up to 15 years in prison, Walsh said.

Everson was indicted June 24 along with her brother, Shawndell Everson, 32, of 313 Village Drive, Apt. 14, and Melissa Ricks, 21, who shares Courtney Everson’s Park Street address. Ricks’ case was put off till July 13.

The grand jury accused the trio of traveling to Cleveland on April 25 to buy a .22-caliber handgun that was brought back to New York concealed in the engine compartment of a rental car. That car and the defendants were stopped the next day by police on the New York State Thruway in the Waterloo area in Seneca County.

The indictment also accused one or more of the trio of making other gun runs. Among those allegations, Shawndell Everson is charged with selling a revolver to Charles Jennings, who allegedly used the weapon in a Nov. 8 shootout with police on North Geddes Street during which he was slain.